Littérature scientifique sur le sujet « True class effect »
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Articles de revues sur le sujet "True class effect"
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Williams, Christopher K. I. « The Effect of Class Imbalance on Precision-Recall Curves ». Neural Computation 33, no 4 (1 avril 2021) : 853–57. http://dx.doi.org/10.1162/neco_a_01362.
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In this note, I study how the precision of a binary classifier depends on the ratio r of positive to negative cases in the test set, as well as the classifier's true and false-positive rates. This relationship allows prediction of how the precision-recall curve will change with r, which seems not to be well known. It also allows prediction of how Fβ and the precision gain and recall gain measures of Flach and Kull (2015) vary with r.
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Rogers, Kim, Phillip M. Campbell, Larry Tadlock, Emet Schneiderman et Peter H. Buschang. « Treatment changes of hypo- and hyperdivergent Class II Herbst patients ». Angle Orthodontist 88, no 1 (10 octobre 2017) : 3–9. http://dx.doi.org/10.2319/060117-369.1.
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ABSTRACT Objectives: To determine the relative effects of Herbst appliance therapy in hypo- and hyperdivergent patients. Materials and Methods: The treated group included 45 growing Class II, division 1, patients treated with stainless steel crown Herbst appliances, followed by fixed edgewise appliances. The untreated control group consisted of 45 Class II, division 1, subjects, matched to the treated sample based on Angle classification, age, sex, and pretreatment mandibular plane angle (MPA). Subjects were categorized as hypo- or hyperdivergent based on their MPAs. Pre- and posttreatment cephalograms were traced and superimposed on cranial base and mandibular structures. Results: The primary effect of the Herbst in terms of maxillomandibular correction was in the maxilla. It significantly restricted maxillary growth, producing a “headgear effect.” Mandibular treatment changes depended on divergence. Hyperdivergent patients experienced a deleterious backward true mandibular rotation with Herbst treatment. Hypodivergent patients, as well as untreated hypo- and hyperdivergent controls, underwent forward true mandibular rotation. However, hypodivergent chins did not advance any more than expected for untreated hypodivergent Class II patients. Conclusions: Hypo- and hyperdivergent patients benefit from the Herbst's headgear effect. While the mandibular growth of hypodivergent patients overcomes the negative rotational effects, hyperdivergent patients undergo a deleterious backward mandibular rotation and increases in facial height.
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Kern, Elisandra Lurdes, Jaime Araujo Cobuci, José Braccini Neto et Darlene dos Santos Daltro. « Relationship between somatic cell score and longevity of Holstein cows in Brazil using a piecewise Weibull proportional-hazard model ». Animal Production Science 59, no 8 (2019) : 1546. http://dx.doi.org/10.1071/an18069.
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The objective of the present work was to evaluate the effect of somatic cell score on the longevity of Holstein cows raised all over Brazil, using a piecewise Weibull proportional-hazard model. The following two longevity traits were defined: true longevity, number of days from first calving to culling; and functional longevity, approximated by correcting true longevity to within-herd-year production. Records on productive life of 131330 cows were used. The model included the time-independent effect of age at first calving. The other effects were time-dependent, and included the following: region by year of calving, variation in herd-size class, milk-production class by year of calving within herd, within-herd milk-production class by number of lactations, within-herd fat content, within-herd protein content, and somatic cell score (SCS). The overall mean of the somatic cell counts (SCC) was 322000 cells/mL. The highest SCC mean was found between 130 to 290 days of lactation. The SCC mean decreased over the years. Cows from Region 5 (Rio Grande do Sul) showed higher SCC means. The risk of culling was slightly higher for functional longevity than for true longevity. The impact of longevity was high in cows from first to fourth lactation with a high SCS, with the risk of culling varying from 0.90 (true longevity: second lactation and Class 2) to 1.2 (functional longevity: fourth lactation and Class 5). Cows at the fifth lactation with a lower SCS had a higher risk of culling (1.4). Including the effect of SCS class by stage of lactation in the models was not beneficial. The decrease in SCS, especially from the first to fourth lactation, can be used for indirect selection to improve the longevity of Holstein cows in Brazil.
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Kaope, Cherfly, et Yoga Pristyanto. « The Effect of Class Imbalance Handling on Datasets Toward Classification Algorithm Performance ». MATRIK : Jurnal Manajemen, Teknik Informatika dan Rekayasa Komputer 22, no 2 (1 mars 2023) : 227–38. http://dx.doi.org/10.30812/matrik.v22i2.2515.
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Class imbalance is a condition where the amount of data in the minority class is smaller than that of the majority class. The impact of the class imbalance in the dataset is the occurrence of minority class misclassification, so it can affect classification performance. Various approaches have been taken to deal with the problem of class imbalances such as the data level approach, algorithmic level approach, and cost-sensitive learning. At the data level, one of the methods used is to apply the sampling method. In this study, the ADASYN, SMOTE, and SMOTE-ENN sampling methods were used to deal with the problem of class imbalance combined with the AdaBoost, K-Nearest Neighbor, and Random Forest classification algorithms. The purpose of this study was to determine the effect of handling class imbalances on the dataset on classification performance. The tests were carried out on five datasets and based on the results of the classification the integration of the ADASYN and Random Forest methods gave better results compared to other model schemes. The criteria used to evaluate include accuracy, precision, true positive rate, true negative rate, and g-mean score. The results of the classification of the integration of the ADASYN and Random Forest methods gave 5% to 10% better than other models.
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Wibowo, Erik, Lauren M. Walker, Shawn Wilyman, Andrew Matthew, Deborah L. McLeod, Richard J. Wassersug et John W. Robinson. « Androgen deprivation therapy educational program : A Canadian true nth initiative. » Journal of Clinical Oncology 34, no 3_suppl (20 janvier 2016) : 243. http://dx.doi.org/10.1200/jco.2016.34.3_suppl.243.
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243 Background: Androgen deprivation therapy (ADT) is commonly prescribed for advanced prostate cancer (PCa) patients, but ADT has many side effects that can impair patients’ quality of life. In various Canadian cities, we are running an educational program to help PCa patients and their partners deal with the side effects of ADT, and maintain a strong relationship with each other while on ADT. Methods: Patients, who are about to start or have been on ADT, and their partners are invited to attend an educational program. Each patient is given a copy of the book Androgen Deprivation Therapy: An essential guide for men with prostate cancer and their partners (Wassersug et al., 2014) and attends a 1.5 hour educational class, where they learn strategies for managing ADT side effects and how to effectively make healthier lifestyle changes using goal-setting exercises. At the end of the class, participants are given the option to attend a monthly follow-up session. To evaluate the effectiveness of the program, participants are asked to complete questionnaire package before attending the class and again 2-3 months later. Results: As of August 2015, 179 patients and 113 partners have attended the ADT Educational Program at Victoria, Vancouver, and Calgary. About 40% of patients returned for the follow-up session. 62 attendees participated in the research evaluation portion of the program. Uniquely designed for this study, the questionnaire package assesses ADT side effect frequency, bother associated with side effects, use of management strategies, and self-efficacy regarding side effect management. An assessment of physical activity and relationship adjustment, and feedback about the class are also included. Conclusions: Patients and partners appreciate being informed about ADT side effects managements and how to make healthier lifestyle changes while on ADT. It remains to be seen how effective the program is in limiting the bother from ADT side effects and helping couples maintain a strong dyadic relationship in the fact of the challenges brought on by ADT. Good enrollment in the in-person program in the 3 cities has propelled the development of the program in Halifax and Toronto starting in fall 2015, and an online version to be available in early 2016.
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Mandour, Yasser Mohammad Hassan, Samer Badie et Mohammad Fahmy Shendy. « Effect of nasal surgery on laryngeal mucosa ». International Journal of Otorhinolaryngology and Head and Neck Surgery 5, no 2 (23 février 2019) : 257. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20190756.
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<p class="abstract"><strong>Background:</strong> The aim of the study was to compare stroboscopic features of laryngeal mucosa before and after the nasal surgery.</p><p class="abstract"><strong>Methods:</strong> Prospective randomized case control study in which 60 patients divided into two groups each include 30 patients, group I with bilateral nasal obstruction due to deviated nasal septum with hypertrophic inferior turbinate, group II bilateral nasal obstruction due nasal polyposis undergoing septoplasty with turbinectomy group I and FESS in group II with video- stroboscopic examination before and 3 months after the surgery for each patient and 30 normal volunteers as a control group. </p><p class="abstract"><strong>Results:</strong> Swollen true vocal cord, laryngeal erythema and laryngeal edema were significantly decreased after the nasal surgery, As Swollen true vocal cord changed from 8 to one patient in group I and from 16 to 4 patients in group II, laryngeal erythema changed from 28 to 6 patients in group I and from 29 to 7 patients in group II and laryngeal edema changed from 28 to 5 patients in group I and from 29 to 8 patients in group II.</p><p class="abstract"><strong>Conclusions:</strong> The nasal surgery would have a significant impact on laryngeal edema, erythema and vocal cord edema.</p><p align="center"><strong><br /></strong></p>
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Kim, Kyoo il. « Efficiency of Average Treatment Effect Estimation When the True Propensity Is Parametric ». Econometrics 7, no 2 (31 mai 2019) : 25. http://dx.doi.org/10.3390/econometrics7020025.
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It is well known that efficient estimation of average treatment effects can be obtained by the method of inverse propensity score weighting, using the estimated propensity score, even when the true one is known. When the true propensity score is unknown but parametric, it is conjectured from the literature that we still need nonparametric propensity score estimation to achieve the efficiency. We formalize this argument and further identify the source of the efficiency loss arising from parametric estimation of the propensity score. We also provide an intuition of why this overfitting is necessary. Our finding suggests that, even when we know that the true propensity score belongs to a parametric class, we still need to estimate the propensity score by a nonparametric method in applications.
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Suprapto, Purwati Kuswarini, Aji Riyanto et Egi Nuryadin. « Wimba learning strategy with PjBL model : How the effect student in excretory system concept ? » Biosfer 13, no 2 (22 octobre 2020) : 292–306. http://dx.doi.org/10.21009/biosferjpb.v13n2.292-306.
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This research aims to determine the effect of wimba learning strategies with project based learning models toward student learning outcomes on the excretory system material. This research was conducted in September 2018 until September 2019. The research method used a true experiment with a population of all class XI in one of the State High School of Tasikmalaya City with 8 classes with a total of 288 students. The samples used were 2 classes taken by cluster random sampling, namely class XI mathematics and science 1 as a controller class and class XI mathematics and science 4 as an experimental class. Based on the results of the study, data analysis using the Ancova test and hypothesis testing can be concluded that there is an influence of the wimba learning strategy with project based learning model toward student learning outcomes on the excretory system material in class XI in one of the State High School of Tasikmalaya City 2018/2019.
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Petrík, Jozef, Peter Blaško, Andrea Vasilňaková, Peter Demeter et Peter Futáš. « INDENTATION SIZE EFFECT OF HEAT TREATED ALUMINUM ALLOY ». Acta Metallurgica Slovaca 25, no 3 (25 septembre 2019) : 166. http://dx.doi.org/10.12776/ams.v25i3.1310.
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<p class="AMStitle">Abstract</p><p class="AMSmaintext">The aim of the submitted work is to study the influence of applied loads ranging from 0.09807 N to 0.9807 N on measured values of micro-hardness of heat treated aluminum alloy 6082. The influence of applied load on a measured value of micro-hardness was evaluated by Meyer’s index n, PSR method and by Analysis of Variance (ANOVA). The influence of the load on the measured value of micro-hardness is statistically significant and the relationship between the applied load and micro-hardness manifests the moderate reverse ISE. As the temperature of the solution treatment rises, the YS/UTS ratio and also Meyer’s index n, measured and “true hardness“ increase. On the other hand, its effect on the plastic properties of the alloy is ambiguous.</p>
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Poluektov, Yuri, AeRyon Kim, Stanislav Khoruzhenko et Scheherazade Sadegh-Nasseri. « The effects of HLA-DO on peptide binding by MHC Class II HLA-DR1 (130.14) ». Journal of Immunology 184, no 1_Supplement (1 avril 2010) : 130.14. http://dx.doi.org/10.4049/jimmunol.184.supp.130.14.
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Abstract Ever since the discovery of the HLA-DOA and HLA-DOB genes in the HLA Class II region, controversy has surrounded their true function. Studies resulting in transcriptional modification of the HLA-DO gene analogs in mice (H-2O) support the general theory that DO decreases the presentation of antigens through the MHC class II system by inhibiting the effects of the MHC class II accessory molecule HLA-DM. The mechanism of such inhibition, however, still remains a mystery. To shed some light on this issue, we have constructed a recombinant form of soluble HLA-DO, without its cytoplasmic anchors, and conducted peptide binding experiments with soluble forms of recombinant HLA-DM and HLA-DR1. Our experiments indicate that DO can have both a negative and a positive effect on peptide presentation by the MHC Class II molecule HLA-DR1, depending on the quality of the anchoring residues of the peptide. In addition, HLA-DO only affects peptide association to the MHC Class II molecules and has virtually no effect on peptide dissociation.
Livres sur le sujet "True class effect"
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Emokhonova, L. G. Naemnyĭ trud vo Frant͡s︡ii : Na puti k postindustrialʹnomu obshchestvu. Moskva : "Nauka", 1991.
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Moore, Clement Clarke. The night before Christmas : A visit from St. Nicholas. San Diego : Browndeer Press, 1999.
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ill, Stevenson Monica, dir. The teddy bears' night before Christmas. New York : Scholastic, 1999.
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Moore, Clement Clarke. La nuit de Noël. [Saint-Lambert, Québec] : Héritage, 1987.
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Moore, Clement Clarke. The night before Christmas. New York : Marshall Cavendish, 2006.
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Moore, Clement Clarke. The night before Christmas. San Francisco : Chronicle Books, 1998.
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Moore, Clement Clarke. 'Twas the night before Christmas. White Plains, N.Y : Peter Pauper Press, 1985.
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Moore, Clement Clarke. The Night Before Christmas. [Mahwah, N.J.] : WhistleStop, 1997.
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Moore, Clement Clarke. The night before Christmas. New York : HarperCollins Publishers, 2006.
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The night before Christmas : A visit from St. Nicholas. Orlando : Harcourt, 2003.
Trouver le texte intégralChapitres de livres sur le sujet "True class effect"
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Chin, Carol, et Hans Krabbendam. « “True Americanism” : The Role of Race and Class in Theodore Roosevelt’s Immigration Policy and Its Effect on US-European Relations ». Dans America's Transatlantic Turn, 65–82. New York : Palgrave Macmillan US, 2012. http://dx.doi.org/10.1057/9781137286499_5.
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Cohen, G. A. « The Workers and the Word : Why Marx Had the Right to Think He Was Right ». Dans Lectures on the History of Moral and Political Philosophy, sous la direction de Jonathan Wolff. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691149004.003.0009.
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This chapter defends Karl Marx against the criticism that he lacks the right to regard his theory as true, insisting that he had the right to think that he was right. To this end, it advances four arguments intended to show that if Marx's theory serves and represents the working class, then it is reasonable to think that it is correct. The first argument relates to Marx's thinking that every class which makes a revolution does so in order to advance its own material interests; the second deals with the suffering of the proletariat in capitalist society; the third concerns the workers' revolutionary struggle, a socialist revolution; and the fourth argument is based on the premise that when a class is secure in its position it needs no illusions. The chapter also considers Reinhold Niebuhr's views on how the proletariat can effect its revolution.
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Agarwal, Isha Y., et Dipti P. Rana. « Fake News and Imbalanced Data Perspective ». Dans Data Preprocessing, Active Learning, and Cost Perceptive Approaches for Resolving Data Imbalance, 195–210. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7371-6.ch011.
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Fake news has grabbed attention lately. In this chapter, the issue is tackled from the point of view of collection of quality data (i.e., instances of fake and real news articles on a balanced distribution of subjects). It is predicted that in the near future, fake news will supersede true news. In the media ecosystem this will create a natural imbalance of data. Due to the unbounded scale and imbalance existence of data, detection of fake news is challenging. The class imbalance problem in fake news is yet to be explored. The problem of imbalance exists as fake news instances increase in some cases more than real news. The goal of this chapter is to demonstrate the effect of class imbalance of real and fake news instances on detection using classification models. This work aims to assist researchers to better resolve the problem by illustrating the precise existence of the relationship between the imbalance and the resulting impact on the output of the classifier. In particular, the authors determine that data imbalance and accuracy are inversely proportional to each other.
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Miller, Michael M., et John F. Peppin. « Introduction ». Dans The Benzodiazepines Crisis, 1–5. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780197517277.003.0001.
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At the same time that it became apparent that overdose toxicity and adverse effects limited the utility of barbiturates to treat anxiety and insomnia, a new class of drugs emerged in the 1950s and 1960s: benzodiazepines. With a rapid onset of action, these new drugs were highly effective in reducing anxiety and promoting sleep when used short term. Rapidly becoming some of the most prescribed drugs in the world, benzodiazepines brought with them a Pandora’s box of potential risks that weren’t at first fully appreciated. Although rarely fatal when taken alone, benzodiazepines have been shown to be correlated with polydrug overdose mortality. With prolonged exposure these drugs can lead to tolerance, physical dependence, and addiction. They can also launch a vicious cycle of rebound after initially relieving anxiety, they can lead to a state of tolerance with the need for increasing doses to achieve the same effect, resulting in more subjectively experienced anxiety. Rebound insomnia is a well-known feature of the long-term use of these agents. Despite these risks, these drugs were extremely popular upon their introduction into the medical marketplace and they became among the most frequently prescribed pharmaceuticals in America, with a variety of agents in this class of drugs being introduced. There then emerged the so-called Z-drugs (e.g., zolpidem and zaleplon), which were marketed as effective sleep aids and “not a benzodiazepine,” with the implication from sales representatives that, without having the molecular structure of benzodiazepines, they would not present the same rebound or adverse effects as benzodiazepines. However, the “Z-drug” agents are indeed benzodiazepine receptor agonists and are associated with the same downsides as agents in the true benzodiazepine drug class.
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Cowper, Elizabeth, Daniel Currie Hall, Bronwyn M. Bjorkman, Rebecca Tollan et Neil Banerjee. « Investigating the past of the futurate present ». Dans Syntactic Features and the Limits of Syntactic Change, 210–38. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198832584.003.0010.
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Using a corpus of 1118 future-referring clauses from each of five versions of the Christian Gospels, this paper explores the effect that the development of English modals as a distinct class had on the range of meanings expressed by the simple present tense. It is shown that in Old English, the simple present tense was the primary form used to express future meanings, while by Early Modern English modals were obligatory in such clauses. In late Middle English, modals were very frequently used, but are shown not to be obligatory. The change is attributed to the advent, in the late 1500s, of a contrastive interpretable feature modality, spelled out by the modals. Thereafter, a clause lacking this contrastive feature could not be interpreted as future-referring except in planned or scheduled contexts. The featural implications of the present-day decline of the true modals are then briefly considered.
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« Is it true that class size does not matter ? A critical review of research on class size effects ». Dans Class Size, 112–24. New York : Routledge, 2016. : Routledge, 2016. http://dx.doi.org/10.4324/9781315760872-16.
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Katz, Wendy Jean. « Native Americans and the West ». Dans A True American, 54–76. Fordham University Press, 2022. http://dx.doi.org/10.5422/fordham/9780823298563.003.0004.
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Walcutt’s pictures of the “West” heroized pioneers, whether legendary but real ones like Simon Kenton, or fictional ones like James Fenimore Cooper’s Leatherstocking. His images appeared in the Know-Nothing Republic, in the Odd Fellows’ annual gift book, in illustrations for a James Rockwood Orton novel, and he joined artists like Tompkins H. Matteson in illustrating Cooper’s turkey shoot. In constructing his natural nobleman, a man shaped by western nature and who because of that is kin to his rivals, American Indians, Walcutt drew on working-class and French Realist consciousness of the value of the ordinary man, even copying a Jean-Francois Millet painting that put an American into the role of folk hero and revolutionary Ivan Mazeppa. But his pictures also corresponded to nativist sympathy for policies of assimilating their fellow native-born Americans and their simultaneous effort to sideline slavery as a threat to the Union.
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Marston, Kendra. « Paranoid Attachments to Suburban Dreams : Reading Pathological Femininity in Gone Girl and The Girl on the Train ». Dans Postfeminist Whiteness, 111–32. Edinburgh University Press, 2018. http://dx.doi.org/10.3366/edinburgh/9781474430296.003.0005.
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Chapter Four analyses the suburban melancholia evident in the psychological thrillers Gone Girl and The Girl on the Train, arguing that the films are examples of an emerging subgenre in which audiences are tasked with assessing whether the heroine’s melancholia harbours an inner violent pathology. Neoliberal postfeminist ideology, here depicted as inciting middle-class female malaise, lends itself to a new kind of (lucrative) cinematic puzzle in which readers or viewers guess the effects on women of a failed social promise. In these two films, the suburban environment, the gothic genre, and the conventions of other quintessentially postfeminist texts provide clues as to the melancholic heroine’s true state of mind.
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Bates, Catherine. « Philip Sidney ». Dans The Oxford History of Poetry in English, 439–55. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780198830696.003.0025.
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Sidney’s secular poetry falls almost exclusively within the genres of lyric and pastoral, both of which presume human relations that are based on difference: in lyric, a difference of gender, in pastoral a difference of class. Sidney thus implies that, as a special kind of speech, poetry is called upon to transact relations that are somehow discrepant or out of sync. When communication is attempted between different classes of being or beings of a different class, an extra effort is required—a rhetoric of courtship, a need for persuasion, for art—that proves quite unnecessary when the parties in question are on a par, speak the same language, and understand each other perfectly. In negotiating relations that are sexually and socially complex, Sidney shows that poetry invariably fails to resolve such differences, and yet in so doing reveals poetry’s true function: which is to assert its formal difference from ordinary speech.
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Patten, Robert L. « Ringing Out Change ». Dans Dickens, Death, and Christmas, 127–68. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780192862662.003.0007.
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Abstract Dickens had associated bells with New Year’s before; in this story they not only ring out the old and ring in the new, but they are misinterpreted by the protagonist, Trotty Veck, as messaging the same thing as the daily news. The Chimes is based on a real event, the trial for murder of a starving unwed mother who slips and falls into the Thames, killing her baby but surviving. The ruling class puts down laborers and suicides; Veck rescues them. As rebel, his odd trotting gait and appetites enshrine the lower-class carnivalesque of Mikhail Bakhtin. Physically able to make life’s journeys, he accepts the crushing verdict of superiors that the poor are unworthy. Like Scrooge, Trotty’s education is effected by spirits—of the bells, who immerse him in a future without hope or life. Once again past, present, and future combine to convert true hearts. Illustrations teach the same lesson.
Actes de conférences sur le sujet "True class effect"
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Ivasishin, Orest, Pavlo Markovsky, Marta Pozuelo et Sergey V. Prikhodko. « Effect of Severe Hot Forging and Rolling on Microstructure, Texture and Tensile Properties of Titanium Metastable Beta-Alloys ». Dans ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63767.
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The influence of specific method of severe hot deformation, forging plus rolling, that ensures true deformation |ε| = 1.39 in single pass was studied on two metastable β-class titanium alloys VT22 (Ti-5.0Al-4.79Mo-4.70V-0.97Fe-0.71Cr) and TIMETAL-LCB (Ti-1.50Al-6.82Mo-4.47Fe), wt%. The results on microstructure, crystallographic texture and tensile properties are presented. It was found that this type of severe deformation forms elongated not-recrystallized β-microstructure with sharp axial (110)β texture, and fine α-precipitates inside the β-grains. In as-deformed condition both alloys are characterized by high tensile strength (above 1500 MPa) and very low ductility. Additional annealing at α + β temperatures does not change β-grain microstructure and crystallographic texture, but gives the structure a balance of strength and ductility. It looks very attractive for practical application of the alloys. Results are discussed in terms of specific mechanism of deformation accommodation.
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Croccolo, Dario, Massimiliano De Agostinis, Stefano Fini, Giorgio Olmi, Francesco Robusto et Nicolò Vincenzi. « Effect of Material and Lubrication Conditions on the Underhead Frictional Response in High Strength Socket-Head Screws ». Dans ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21506.
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Abstract The present paper investigates the influence of several design parameters on the frictional response at the underhead in a bolted joint, involving high strength socket-head screws: M8 class 14.9 with black oxidization coating. The experimentation deals with different underhead materials (Steel, Aluminium), lubrication conditions (dry, lubricated) and repeated tightening operations. The awareness of the actual friction coefficients, depending on the current operating parameters, is a useful tool, to support the most proper design of a bolted joint. The experimental campaign has been run by a testing rig for friction coefficient estimation, complying with the recommendations by International Standard ISO 16047 and the automotive Standard VW01131-1 in order to consider the effect of the tightening speed normally adopted in the automotive field. The axial preload generated upon tightening induces a high pressure on the remarkably small underhead surface of the utilized high strength socket-head screws and is therefore likely to affect the tribological response. Consequently, some differences may be expected with respect to the tribological behavior of screws belonging to lower strength grades. This is particularly true, when tightening is done without bearing lubrication, and through several repeated assembly-disassembly operations. The collected data have been processed by the tools of ANOVA and F-Test, in order to assess the significance of each factor, as well as related interactions.
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Al-Ballam, S., H. Karami et D. Devegowda. « A Hybrid Physical and Machine Learning Model to Diagnose Failures in Electrical Submersible Pumps ». Dans SPE/IADC Middle East Drilling Technology Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/214632-ms.
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Abstract Electrical submersible pumps (ESPs) are among the most common artificial lift techniques in highly productive oil wells. The ESP failures are extremely costly to the producers and must be minimized. This study proposes a hybrid approach utilizing multi-class classification machine learning (ML) models to identify various specific failure modes (SFMs) of an ESP. A comprehensive dataset and various ML algorithms are utilized, considering the physics of fluid flow through the ESP. The ML models are based on field data gathered from the surface and downhole ESP monitoring equipment over five years of production of 10 wells. The dataset includes the failure cause, duration of downtime, the corresponding high-frequency (per minute) pump data, and well-production data. The prediction periods of 3 hours to 7 days before the failure are evaluated to minimize false alarms and predict the true events. Four modeling designs are used to handle the data and predict ESP failure. These designs differ in the input parameters used for the model and signify the effect of including the physical parameters in failure prediction. Several ML models are tested and evaluated using precision, recall, and F1-score performance measures. The K-Nearest Neighbor (KNN) model outperforms the other algorithms in forecasting ESP failures. Some other tested models are Random Forest (RF), Decision Tree (DT), Multilayer Perceptron (MLP) Neural Network, etc. According to the data, most ESP operational failures are characterized as electrical failures. The ML models show similarly good performances with high true prediction rates in predicting ESP failures for all the tested designs. The design that integrates the effects of gas presence and pump efficiency while minimizing the number of input variables is suggested for general use. Increasing the prediction period up to 3 days results in a negligible drop in the model’s performance, showing that the model can predict ESP failures accurately three days before their occurrences. However, the forecasts show increases in missed failures and false alarms for prediction periods of more than three days, making three days the selected prediction period. These ML models will aid operators in avoiding undesirable events, reducing downtime, and extending the lifespan of ESPs. ESP failures are unanticipated but common occurrences in oil and gas wells. It is necessary to detect the onset of failures early and prevent excessive downtime. This study’s model allows engineers to detect failures early, diagnose potential causes, and propose preventive actions. It is crucial in transitioning from a reactive event-based to proactive and predictive maintenance of artificial lift operations.
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Zaev, Ivan, Sergey Smirnov et Andrey Kostukov. « Analysis of the Multi-Zone SI-Engine Model for Fuel-Flexible Engine Design Applications ». Dans WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0180.
Texte intégralRésumé :
<div class="section abstract"><div class="htmlview paragraph">Development of fuel-flexible spark-ignition engines, working on CNG, LPG, hydrogen-enriched fuels or with mixtures of gaseous fuel/gasoline requires models for prediction of heat release rate, which can capture the effect of fuel composition and combustion chamber geometry on engine performance and emissions. Multi-zone models with explicit tracking of turbulent flame surface can be used for this purpose. Coupled with detailed chemical kinetic mechanisms, these models can also predict self-ignition of unburned charge ahead of the flame front. When optimizing engine performance and emissions in a fuel-flexible mode, the key question is sensitivity of the multi-zone model parameters to the properties of the fuel. In the present work, the multi-zone model of the CFR engine is developed based on Blizard-Keck eddy burn-up flame propagation approach for prediction of flame propagation and heat release rate. Model parameters are time constant for flame development, eddy entrainment rate constant for unburned mixture, time constant of burn-up in turbulent eddies. The simulations are performed for number of fuels: PRF and LPG components. The set of mentioned parameters is determined for every fuel and corresponding compression ratios used in experiments. It is shown that these parameters demonstrate only a slight sensitivity to fuel selected and can be used for prediction of fuel effects on engine performance. It is identified that for the model parameters to be true constants, the correct selection of turbulence integral length scale is required. Also, it is shown that the accurate correlation for laminar flame speed as function of unburned mixture state is required for the model to provide reasonable accuracy and predictive capability. New laminar flame speed correlations for n-butane, iso-butane and propylene are proposed.</div></div>
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Grant, P. J., K. K. Hampton, P. G. Wiles et C. R. M. Prentice. « THE EFFECTS OF VASOPRESSIN ON FIBRINOLYSIS AND FACTOR VIII ARE NOT MEDIATED THROUGH V2 RECEPTORS ». Dans XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644712.
Texte intégralRésumé :
Vasopressin (aVP) mediates its effects on smooth muscle through V1 receptors and on the kidney via pharmacologically distinct V2 receptors. Infusions of aVP and its long acting synthetic analogue DDAVP both produce increases in factor VIII and fibrinolytic activity in man. V1 receptors are known not to mediate this effect, however it has been suggested that the FVIII response might be mediated by V2 receptors as patients with nephrogenic diabetes insipidus are reported to have no FVIII response to DDAVP. It remains unclear whether this is a true phenomenon or reflects tachyphylaxis to the high vasopressin levels found in nephrogenic diabetes insipidus. The aim of this study was to investigate whether the pharmacological V2 receptor blocker lithium alters the effect of aVP infusions on FVIII and fibrinolysis in man. 4 control subjects and 6 patients taking long term lithium therapy (mean serum lithium 1.09 mmbl/l) were infused with 2.0 units aVP over 1 hour. Samples were collected for assay of aVP, euglobulin clot lysis time (ECLT) and FVIII coagulant activity (FVIIIC) before and at the end of infusion. In the control subjects median aVP rose from 0.5 to 83 pg/ml at the end of infusion. FVIIIC rose frcm 100 to 333% and plasminogen activator activity (PAA: 106 /ECLT) from 198 to 437 units. In the lithium treated group median aVP rose frcm 0.5 to 68 pg/ml at the end of infusion. FVIIIC rose from 100 to 263% and PAA from 102 to 453 units. There was a significant correlation between the plasma aVP and FVIIIC (r = 0.89 p < 0.005) and PAA (r = 0.92 p < 0.001) in the control group and the lithium treated group (FVIIIC r = 0.81 p < 0.002; PAA r = 0.69 p < 0.02). There was no significant difference between the rise in either FVIIIC or PAA in the lithium treated group compared with controls. These results do not support the hypothesis that the action of aVP on FVIII or fibrinolysis is mediated by V2 receptors. The effects of aVP on haemostasis may either be mediated directly through a third class of receptor or indirectly by the release of an intermediate hormone.
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Magiru, Anca, et Ionel Magiru. « ENGLISH FOR LAW STUDENTS : THE CASE STUDY METHOD ». Dans eLSE 2013. Carol I National Defence University Publishing House, 2013. http://dx.doi.org/10.12753/2066-026x-13-125.
Texte intégralRésumé :
The paper intends to prove that the English lesson for the law students of English should be special, productive and also fun in order to get good results and personal satisfaction, to exercise the students' minds and their reasoning powers. Taken into account these purposes, the paper will focus on the case study method which has got an emphatic active-participatory and formative effect, being a dynamic way of learning which wants special conditions for an efficient solving of the case. What we really should do in the class is to select cases from the 20th century which are the subjects of appeal to a higher court indicating that the point of law involved is difficult and causes reasonable jurists to disagree over the result. On appeal, many of the judgments are not unanimous, this further showing that the legal issues are not easy. The cases should be consistent with the general current of the law in the United States of America and in the other common law countries. The results in the cases should not be arbitrary.The method, with a bilateral, interactive and reciprocal character, will make students love ruling as judges and/or jury on true courtroom cases that give them a chance to defend the accused. The method will help students develop and improve: a. their legal conscience and thinking, b.their legal principles, feelings and attitudes, c. and their legal ability, practice and usage. It will motivate the students to love the truth and be honest and correct people.
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Tomic, Aleksandar, et Shahani Kariyawasam. « Critical Review of Risk Criteria for Natural Gas Pipelines ». Dans 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64356.
Texte intégralRésumé :
Risk Assessment is an integral part of an Integrity Management Program (IMP), and it is generally the first step in most IMPs. Risk is of the product of two variables, the likelihood of failure and the consequence of failure, where failure is defined as a loss of containment event. Hence, it is necessary to calculate both variables in order to accurately model risk. To assess risk, criterion need to be established and the actual risk needs to be compared to the criterion in order to determine the acceptability of risk. Currently, most industry risk assessment models are qualitative risk models, where consequence is generally characterized by class, relative population measures, or some other relative measure. While this may be adequate for some relative risk ranking purposes, it is generally not accurate in representing the true consequences and the arbitrary nature leads to overly conservative or overly un-conservative results. Conversely, Quantitative Risk Assessment (QRA) models take into account the effect of the thermal radiation due to ignited pipeline rupture and evaluate the consequence on the surrounding human population. Such a consequence model is dependent on the pipeline properties (i.e. diameter and MOP) and the structure properties (i.e. precise locations and types of structures). The overall risk is then represented by two specific, well defined measures: Individual Risk (IR) and Societal Risk (SR). The goal of this paper is to perform a critical review of IR and SR acceptability criteria that are widely available and widely used, and outline the criteria (and the approach) adapted by TransCanada Pipelines. Worldwide, there are several different standards that define the criteria for evaluating IR and SR, particularly some countries with higher population densities around pipelines (e.g. UK and Netherlands). These IR and SR criteria have been compared in a hypothetical case study, to determine the most appropriate method in terms of the assumptions for calculating risks, the criteria, and how the actual risks compares to the criteria. The outcome of this study was the adoption of a defendable process for calculating SR, along with the associated criterion.
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Rizzuto, Enrico. « Including Roll in the Evaluation of Bending Loads for the Hull Girder in a Seaway ». Dans ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51401.
Texte intégralRésumé :
The longitudinal strength of the hull girder is traditionally verified by linear superposition of still water (static) loads to wave induced (dynamic) loads. Belonging to the former class, gravitational effects are considered always as directed along the plane of symmetry of the ship, as the static equilibrium position corresponds to the ship floating with a neutral heel angle. This is not the case for a ship in a seaway, as the weight will act in reality along the instantaneous ‘true vertical’, which is not in general contained in the symmetry plane, due to ship motions. The actual direction of the weight force represents one of the non-linear aspects of the seakeeping problem, as the direction of one of the input external forces (weight) depends on the instantaneous roll angle (representing an output of the study). The present paper investigates the above subject, trying to quantify this retro-action effect with reference to the verification of the bending strength of the hull girder. The attention is focussed on the magnitude of the horizontal bending component generated by the inclined direction of the weight force as compared to the bending component induced by waves in the same plane (normal to the plane of symmetry of the ship). The subject is discussed on the basis of a linear seakeeping analysis, which is not able to model properly the non-linear aspects above recalled, but provides anyway as output an estimate of roll motions that can be used to evaluate in a qualitative way how large would be the horizontal load component due to weight, not accounted for in equilibrium equations. The statistical correlation between the wave induced bending load and roll angle is treated with the simplified assumption of a Gaussian joint distribution and a consistent model for the combination of horizontal and vertical bending components is established. The reference situation is chosen as corresponding to the extreme value of the vertical wave induced component, and distribution for the horizontal wave bending component and of roll motion are conditioned to the occurrence of such extreme value. This can be seen as an extension of Turkstra’s rule for the combination of loads to the case of correlated loads. The stochastic model is applied in the evaluation of the hull girder reliability for a test case and the conditioned probability distribution of roll motion at the failure point is derived in order to discuss the influence of a possible inclusion of roll effects in the verification of the hull girder bending strength.
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Crucean, Stefan. « Principalii dăunători ale culturii nucifere din clasa Arachnida și manifestarea efectelor negative ale acestora ». Dans International Scientific Symposium "Plant Protection – Achievements and Prospects". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2020. http://dx.doi.org/10.53040/9789975347204.04.
Texte intégralRésumé :
This material results from the research of the nut culture in order to identify pathogenic organisms of the class Arachnida and to represent the effects of these organisms on tree organs. The research was made at the Botanical Garden Institute, Chișinău on a number of 300 trees. This paper includes the identification of the main pests of the class Arachnida, namely: the gall mite of walnut leaves (Aceria tristriata) and the disease named walnut blister mine caused by Aceria erinea. At the same time, the methods of pest control and the negative effects of their presence are exposed here.
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Herber, Daniel R., Tinghao Guo et James T. Allison. « Enumeration of Architectures With Perfect Matchings ». Dans ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60212.
Texte intégralRésumé :
In this article a class of architecture design problems is explored with perfect matchings. A perfect matching in a graph is a set of edges such that every vertex is present in exactly one edge. The perfect matching approach has many desirable properties such as complete design space coverage. Improving on the pure perfect matching approach, a tree search algorithm is developed that more efficiently covers the same design space. The effect of specific network structure constraints and colored graph isomorphisms on the desired design space is demonstrated. This is accomplished by determining all unique feasible graphs for a select number of architecture problems, explicitly demonstrating the specific challenges of architecture design. Additional applications of this work to the larger architecture design process is also discussed.
Rapports d'organisations sur le sujet "True class effect"
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Perkins, Dustin. Invasive exotic plant monitoring at Colorado National Monument : 2019 field season. Sous la direction de Alice Wondrak Biel. National Park Service, juillet 2021. http://dx.doi.org/10.36967/nrr-2286650.
Texte intégralRésumé :
Invasive exotic plant (IEP) species are a significant threat to natural ecosystem integrity and biodiversity, and controlling them is a high priority for the National Park Service. The North-ern Colorado Plateau Network (NCPN) selected the early detection of IEPs as one of 11 monitoring protocols to be implemented as part of its long-term monitoring program. This report represents work completed at Colorado National Monument during 2019. During monitoring conducted June 12–19, a total of 20 IEP species were detected on monitoring routes and transects. Of these, 12 were priority species that accounted for 791 separate IEP patches. IEPs were most prevalent along riparian areas. Yellow sweetclover (Melilotis officinale) and yellow salsify (Tragopogon dubius) were the most commonly detected priority IEPs along monitoring routes, representing 73% of all priority patches. Patches of less than 40 m2 were typical of nearly all priority IEP species except yellow sweetclover. A patch management index (PMI) was created by combining patch size class and percent cover for each patch. In 2019, a large majority of priority IEP patches were assigned a PMI score of low (46%) or very low (50%), indicating small and/or sparse patches where control is generally still feasible. This is similar to the numbers for 2017, when 99% of patches scored low or very low in PMI. Seventy-eight percent of tree patches were classified as seedlings or saplings, which require less effort to control than mature trees. Cheatgrass (Anisantha tectorum) was the most common IEP recorded in transects, found in 30–77% of transects across the different routes. It was the only species found in transects on all monitoring routes. When treated and untreated extra areas near the West Entrance were compared, the treated area had comparable or higher lev-els of IEPs than the untreated area. When segments of monitoring routes conducted between 2003 and 2019 were compared, results were mixed, due to the different species monitored in different time periods. But in general, the number of IEPs per 100 meters is increasing or remaining constant over time. There were notable increases in IEP patches per 100 meters on several routes in 2019: field bindweed (Convolvulus arvensis) along East Glade Park Road; Siberian elm (Ulmus pumila) in Red Canyon; yellow salsify along East Glade Park Road, No Thoroughfare Canyon, No Thoroughfare Trail, and Red Canyon; and yellow sweetclover in No Thoroughfare Canyon and Red Canyon. Network staff will return to re-sample monitoring routes in 2021.